溶质类型与矿化度对土壤持水特性的影响

Effect of Solute Type and Salinity on Soil Water Retention Curve

土壤水分特征曲线是研究土壤水分运动与调控等方面的重要科学依据。以往土壤水分特性曲线的研究关注土壤孔隙特性的影响,而对土壤液体的影响关注较少。为此,本研究以甘肃省秦安县果园黑麻土为研究对象,采用室内模拟的方法,研究了不同矿化度(0、1、3、5、10 g L-1)的NaCl和Na2SO4溶液对土壤脱水曲线及拟合参数的影响。结果表明:水质的矿化度对土壤饱和含水量有一定的影响,低矿化度(【3 g L-1)仅对低吸力段(pF【2.5)水分特征曲线有影响,高矿化度(≥3 g L-1)对整个吸力段(pF在0~4.2)水分特征曲线有影响,其中矿化度为5 g L-1的NaCl和Na2SO4处理土壤容积含水量最小,且较对照差异最大。相同矿化度的NaCl和Na2SO4溶液对土壤水分特征曲线参数变化率的影响程度不同,对α的影响最为显著,其次为θs,再次为n。NaCl对参数α和n变化率的影响均随矿化度的增大呈先增加后降低趋势,而Na2SO4对参数α和n变化率的影响随矿化度的增大呈先降低后增大的趋势,且NaCl对土壤持水特性的影响大于Na2SO4。

Soil water retention curve provides the important scientific basis for studying the movement and control of soil water. So far, most related researches and achievements have showed that soil properties have a certain impact on the soil water retention curve, but seldom has the academic circle attached importance to characteristics of liquid film. Therefore, the subject of study is black gunny soils in orchards in Zhengchuan Village of Qin'an County in Gansu Province. And we investigate the influence of NaCl and Na2SO4solutions of different salinity(0, 1, 3, 5 and 10 g L-1) on the soils water retention curve and the parameters of Van Genuchten equation using a centrifuge method. The results show that the salinity has a certain impact on the content of saturated water: the lower salinity( < 3 g L-1) has impact on the soil water holding curve within low suctions(pF < 2.5), but the higher salinity(≥ 3 g L-1) has impact on soil water holding curve within suctions(pF within 0 ~ 4.2). The content of soil moisture(θv) is the lowest by treated with the NaCl and Na2SO4solutions of salinity = 5 g L-1, and the treatments are significantly different with the control(salinity = 0 g L-1). The influence of salt type on variety velocity of parameters of Van Genuchten equation is different under equal salinity. Salt type has more obvious influence on the parameter α than the parameters θsand n, and the parameter n has a minimum influence. The parameters of variety velocity, i.e. a and n, are both significantly increased at the initial stage and then decreased with the increase of the salinity of NaCl, but the parameters of variety velocity, i.e. a and n, were both significantly decreased firstly and then increased with the increase of the salinity of Na2SO4. The NaCl solution has greater influence on soil water holding curve than Na2SO4.